Conventionally, an electric power converter that converts an electric power by using two inverters is known in the art. For example, a patent document, JP 2011-188674 (Patent document 1) discloses a ripple current reduction scheme that varies a shift value of both of a first duty center value that concerns a voltage applied to a first winding wire group, and a second duty center value that concerns a voltage applied to a second winding wire group, for the reduction of a ripple current together with a prevention of uneven heat loss.
Further, in the patent document 1, for a distribution of heat generation, a shift direction of a duty instruction signal is periodically switched. Furthermore, in the patent document 1, switching of the shift direction of the duty instruction signal is controlled, i.e., is set to have certain switching cycle, in consideration of a noise sound due to such a switching of the shift direction. However, the patent document 1 is silent about a frequency-considered control of the phase current.